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New Scientist Live

Natural immunity may protect Peruvians from rabies

HERE’S a study with bite. A group of Peruvians thought to have survived untreated rabies infection have bucked the notion that the virus is lethal to humans.

A team led by Amy Gilbert of the US Centers for Disease Control and Prevention, collaborating with Peru’s Ministry of Health, visited two communities in a remote part of the Peruvian Amazon. Outbreaks of rabies infection caused by bites from vampire bats have been documented regularly in Peru over recent decades.

When the team sampled the blood of 63 people from these communities they found that seven of them had rabies-virus-neutralising antibodies. One of these people had received a rabies vaccine but the other six had not, though they reported having been bitten by bats in the past.

The antibodies are produced when the body is directly exposed to rabies or exposed to a vaccine for the virus. The team concluded that the six unvaccinated people with the antibodies must have been exposed to rabies without dying from it, suggesting they have a natural immunity (American Journal of Tropical Medicine and Hygiene, DOI&colon; 10.4269/ajtmh.2012.11-0689).

The researchers admit that they don’t yet know whether these people actually developed symptoms of an infection and recovered or were exposed to a small dose of the virus which they were able to fight off. Regardless, if further studies confirm that there are populations of people with a greater natural immunity to rabies, the discovery could pave the way for new treatments.